Colorado River Cutthroat deemed ineligible for Endangered Species Act list

The U.S. Fish and Wildlife Service has concluded that a petition to list the Colorado River Cutthroat trout as threatened or endangered under the Endangered Species Act does not provide substantial biological information to indicate that a listing may be warranted at this time.

The Center for Biological Diversity, the Biodiversity Legal Foundation, Biodiversity Associates, Ancient Forest Rescue, Southwest Trout, Wild Utah Forest Campaign, Colorado Wild and an individual, Mr. Noah Greenwald, petitioned the Service to list the Colorado River cutthroat trout in its occupied habitat within its known historical range.

While the Colorado River cutthroat trout has declined from historic levels, the most recent biological information and surveys indicate that a significant number of viable, self-sustaining, and well-distributed populations are found throughout its historical range, said Ralph Morgenweck, Director of the Mountain-Prairie Region.

"The hard work of our state, federal, tribal, and private partners is paying off," he commented. "Their ongoing conservation efforts are responsible for the improved status of this native fish. Their continued efforts will ensure its long-term prosperity."

State agencies representing Utah, Colorado and Wyoming as well as the USDA-Forest Service, Bureau of Land Management, National Park Service, the Ute Indian Tribe and the USFW formed a task force to address range-wide conservation efforts for Colorado River cutthroat trout. The task force developed conservation measures for the species in Colorado, Utah and Wyoming. It has been implementing these measures for several years.

In addition to reviewing the petition and supporting documentation, USFW examined information that was contained in its files or readily available. USFW found that:

Colorado, Utah and Wyoming report 327 conservation populations - fish that are more than 90 percent pure Colorado River cutthroat trout. Of these, 286 populations occupy approximately 1,010 stream miles and 41 populations occupy approximately 1,124 acres of lakes.

These populations include 221 core conservation populations, fish that are more than 99 percent pure Colorado River cutthroat trout, in approximately 684 stream miles and 30 core conservation populations in approximately 545 acres of lakes.

Fifty-three percent of existing core conservation populations are currently protected by a natural or artificial barrier to prevent intrusions by non-native fish.

With regard to the petition, USFW concurred that certain land management practices such as overgrazing and water diversions can have a negative impact on Colorado cutthroat trout habitat. However, it was decided that the petition did not recognize the ongoing efforts of the state and federal land management agencies to protect and conserve Colorado River cutthroat trout populations and habitat.

These agencies have also instituted fishing regulations and prohibited nonnative stocking near core or conservation populations.

USFW also acknowledges that hybridization does occur in some Colorado River cutthroat trout populations. But many populations are more than 99 percent pure Colorado River cutthroat trout - and the states of Utah, Colorado and Wyoming have implemented policies to protect the genetic purity of the core populations.

According to Morgenweck, whirling disease is a significant concern for trout in general, but few Colorado River cutthroat trout populations have tested positive for the disease, and Utah, Colorado and Wyoming are implementing management actions to protect Colorado cutthroat trout from whirling disease.

Also, the whirling disease pathogen is said to be unlikely to proliferate in much of the habitat for the Colorado River cutthroat trout because this species is generally found at higher elevations, where the water is too cold for the pathogen to survive.

The Colorado River cutthroat trout is the only salmonid native to the upper Colorado River basin. It is distinguished by its red/orange slash marks on both sides of the lower jaws and relatively large spots concentrated on the posterior part of the body.

The Colorado River cutthroat trout currently occupy portions of the Colorado River drainage in eastern Utah, Colorado and southern Wyoming and may still occur in very limited areas of New Mexico and Arizona.